Activated-sludge treatment.



UNITEn STATES. PATENT OFFICE.

GUY I4. NOBLE,

or'cnroaeo, rumors, assrc von 'ro anmorm AND ooatrm, or

onroaeo, rumors, a conronnrron or nnmors.

ACTIVATEDvSLUDGE TREATMENT.

1,254,841. No Drawing.

tuga w der range of usefulness and in experimentation to increase its efliciency and econoinicalavailability.

- Briefl*y jand generally stated, the activated I sludge treatment of sewage conslsts in conducting the r'awsewage into and through aerating;tanks'Frovided with means for t e 1 sti ling intjr'od-uctionb .air under pressure to tie bottom otthe tank,,whereby the air is caused to bubble-upfthrough the liquid sewage. The passage of the air through the sewage develops. in time microscopic aerobic or an isms whi chin the course of their growt i or by means Uf-j-COfldltlOIlS provided by their growth, oxidize the colloidal and soluble solids in the' -sewage causing them to septank where it is allowed toiremain quiescent for from thirty minutes to one 'hour, and the solids settle to the bottom as a I flocculent ooze, called activated sludge.

The remaining liquid content of the sewa e is rendered erfectly clear, white and odorless. This e uent liquid may then be run oil through the sewers to rivers or other natural channels without injury to fish or m'enaceto the health or comfort of people living adjacent thereto.

' The activated sludge is removed from the bottom of the tank, to be freed of its water. content, and when dried is. available as a fertilizer, containin a large percentage of ammonia compoun s and being practically 'free from any offensive odors.

.To make the process continuous. and in order to hasten the treatment of the raw Specification of Letters Patent.

flocculent particles. The treated the proper stage is run into aabout three;

- signed my name scribing witnesses.

sewage, it is found advantageous to inoculate the same upon its introduction to. the aerating tanks with activated sludge from sewage previously treated, wherebyithe process is reduced in point of time from several days to a few hours.

I have disco vered that during the settling by which is obtained the activated process, sludge used in the inoculation of the fresh sewage, there is a second development of anaerobic organisms and a deterioration in the virility of the aerobic or anisms due to the necessary cessation of t e air supply while settling is taking place whereby its inoculating efiiciency'is reduced.

I have discovered that the number and virility of the aerobic organ sms in the acti-' vated sludge, and its consequent value. as an 4 i inoculating medium, are greatly increased by a. further aeration of the sludge subsequent .to its withdrawal from the settling chamber and previous to'its introduction to the raw sewage, the best results being ob- 76' tained by aerating the same about three hours. I claim: I

1. The improvement in I the activated for a period of Patented Jan. 29,1918.

Application filed July 9, 1917. Serial No. 179,458. i I

sludge method of treatment as applied to sewage, which consists in drawing ofi the activated sludge from previously treated sewage, aerating such slud e after its withdrawal to enhance the virility of the aerobic organisms therein, and inoculatin the raw sewage with such re-vitalized slu ge. 2. The improvement in the activated sludgemethod of treatment as applied to sewage, which consists in drawing ofi the activated sludge from previously treated sewage, aerating-such sludge for a period of hours after its withdrawalfto enhance the virility of the. aerobic'organisms therein, and inoculating the raw sewage with such re-vitalized sludge.-

In testimony whereof I have hereunto in the presence, of two sub,-

.Witnesses: I

A. B. S..WAr.-ron, GaMcDoNaLn.

G YL. NOBLE. r 

